Reciprocating pump

Abstract

A reciprocating pump comprising a cylinder and a plunger reciprocable in the cylinder, a member at one end of the cylinder having an axial passage in which the plunger is axially slidable, and a seal between the member and the plunger. The pump is characterized in having a sleeve for protecting the seal from the effects of relatively high pressure and pressure fluctuations of fluid in the cylinder. The sleeve surrounds the plunger and is fixed in position inwardly of the member and has an axial bore in line with the axial passage in the member. The sleeve blocks communication from within the cylinder to the axial passage in the member except for such communication as there may be through the bore in the sleeve to the axial passage in the member. The plunger is axially slidable in the bore. The sleeve has internal grooving establishing a pressure reducing path for fluid from the inner to the outer end of the sleeve for reducing the pressure and fluctuations in pressure of fluid from the cylinder on the seal.

What is claimed is: 
     
       1. A reciprocating pump comprising a cylinder and a plunger reciprocal therein, a member at one end of the cylinder having an axial passage in which the plunger is axially slidable and a seal between said member and the plunger, and characterized in having means for protecting the seal from the effects of relatively high pressure and pressure fluctuations of fluid in the cylinder comprising a sleeve surrounding the plunger, said sleeve being separate from said member and disposed in its entirety inwardly of said member and the seal, said sleeve having an axial bore in line with said axial passage in said member and blocking communication from within the cylinder to said axial passage in said member and the seal except for such communication as there may be through said bore in said sleeve to said axial passage in said member, said plunger being axially slidable in said bore, said sleeve having a series of annular internal grooves therein spaced axially thereof establishing a pressure-reducing path from the inner to the outer end of said sleeve for reducing the pressure and fluctuations in pressure of material from the cylinder on the seal. 
     
     
       2. A reciprocating pump as set forth in claim 1 having means at the outer end of said member for scraping the plunger. 
     
     
       3. A reciprocating pump as set forth in claim 1 wherein the sleeve has means at its outer end in sealing engagement with respect to the cylinder for blocking communication from within the cylinder to said axial passage in said member except for such communication as there may be through said bore in the sleeve to said axial passage in said member. 
     
     
       4. A reciprocating pump as set forth in claim 3 wherein the seal is at the inner end of said member and said member holds the seal compressed against the outer end of the sleeve and holds the sleeve in place. 
     
     
       5. A reciprocating pump as set forth in claim 4 wherein the grooving in the sleeve comprises a series of annular internal grooves in the sleeve spaced axially of the sleeve. 
     
     
       6. A reciprocating pump comprising a cylinder and a plunger reciprocal therein, a member at one end of the cylinder having an axial passage in which the plunger is axially slidable and a seal between said member and the plunger, and characterized in having means for protecting the seal from the effects of relatively high pressure and pressure fluctuations of fluid in the cylinder comprising a sleeve surrounding the plunger fixed in position inwardly of said member having an axial bore in line with said axial passage in said member and blocking commumication from within the cylinder to said axial passage in said member except for such communication as there may be through said bore in the sleeve to said axial passage in said member, said plunger being axially slidable in said bore, said sleeve having internal grooving establishing a pressure-reducing path from the inner to the outer end of said sleeve for reducing the pressure and fluctuations in pressure of material from the cylinder on the seal, and wherein said reciprocating pump further comprises a head at said one end of the cylinder, said head having a bore in line with the cylinder and a counterbore at the outer end thereof providing an outwardly facing annular shoulder at the inner end of the counterbore, said sleeve having an outwardly extending peripheral flange at its outer end engaging said shoulder, said member comprising a bushing having an outwardly extending annular flange and an annular recess at its inner end, the seal being an annular seal received in the recess, a gland threaded in the counterbore with the inner end of the gland engaging the flange on the bushing and with the inner end of the bushing holding the flange on said sleeve in sealing engagement with said annular shoulder and holding the seal compressed against the outer end of said sleeve. 
     
     
       7. A reciprocating pump as set forth in claim 6 having a seal between the bushing and the head. 
     
     
       8. A reciprocating pump as set forth in claim 6 having means for scraping the plunger held against the outer end of the bushing by the gland. 
     
     
       9. A reciprocating pump as set forth in claim 8 wherein the scraping means comprises a split ring surrounding the plunger at the outer end of the bushing and a spring ring around said split ring for contracting the split ring for scraping engagement with the plunger. 
     
     
       10. A reciprocating pump as set forth in claim 9 wherein the gland has a counterbore at the inner end thereof providing an inwardly facing annular shoulder at the outer end of the gland counterbore, and wherein the reciprocating pump further comprises an annular spacer engaging said inwardly facing gland shoulder and the outwardly facing end of the bushing, said scraping means being held between the spacer and said outwardly facing end of the bushing. 
     
     
       11. A reciprocating pump as set forth in claim 6 wherein the grooving in the sleeve comprises a series of annular internal grooves in the sleeve spaced axially of the sleeve. 
     
     
       12. A reciprocating pump as set forth in claim 11 wherein the sleeve is tapered, diminishing in outside diameter toward its inner end, and the grooves are of diminishing outer diameter from the outermost to the innermost groove.